Re: [Discuss-gnuradio] File sink causes "S" errors

Hi,

Try /dev/random instead of /dev/zero. SSDs are known to use data compression algorithms to run-length-encode drive data on the fly, to increase bandwidth and reduce data replication on the drive. It's possible that your drive is performing write optimization on your test which is not applicable to the real world.     

 If you want a speed benchmark you probably want /dev/urandom instad of /dev/random, because /dev/random will block when it runs out of high-quality random numbers.    

I've used /dev/urandom output from a file

> dd if=/dev/urandom of=random.bin bs=1K count=10000000

> dd if=random.bin of=/SSD/test.bin bs=1K count=1000000
1000000+0 records in
1000000+0 records out
1024000000 bytes (1.0 GB) copied, 11.1116 s, 92.2 MB/s
> dd if=random.bin of=/SSD/test.bin bs=10K count=100000
100000+0 records in
100000+0 records out
1024000000 bytes (1.0 GB) copied, 9.74512 s, 105 MB/s
> dd if=random.bin of=/SSD/test.bin bs=100K count=10000
10000+0 records in
10000+0 records out
1024000000 bytes (1.0 GB) copied, 9.38715 s, 109 MB/s
> dd if=random.bin of=/SSD/test.bin bs=1000K count=1000
1000+0 records in
1000+0 records out
1024000000 bytes (1.0 GB) copied, 9.38381 s, 109 MB/s
> dd if=random.bin of=/SSD/test.bin bs=10000K count=100
100+0 records in
100+0 records out
1024000000 bytes (1.0 GB) copied, 9.29913 s, 110 MB/s

If I read directly  from /dev/urandom the whole performance goes down as random numbers can be generated fast enough....

Thanks,
   Thomas

--  ****************************************************************** Dr. Thomas Hobiger Space-Time Measurement Project Space-Time Standards Group New Generation Network Research Center National Institute of Information and Communications Technology ------------------------------------------------------------------ 4-2-1 Nukui-Kitamachi, Koganei 184-8795 Tokyo Japan ------------------------------------------------------------------ email:  hobiger@nict.go.jp phone:  ++81-042-327-7561 fax:    ++81-042-327-6664 ------------------------------------------------------------------ homepage (priv.): http://www.hobiger.org ******************************************************************